Re: [Qemu-devel] [PATCH v2 0/2] block/ssh: Implement .bdrv_refresh_filename()

[Max Reitz <mreitz@redhat.com>]

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On 06.02.19 17:37, Richard W.M. Jones wrote:
> On Wed, Feb 06, 2019 at 04:29:17PM +0100, Max Reitz wrote:
>> This series implements .bdrv_refresh_filename() for the ssh block
>> driver, along with an appropriate .bdrv_dirname() so we don't chop off
>> query strings for backing files with relative filenames.
>>
>> This series depends on my "block: Fix some filename generation issues"
>> series.
>>
>> Based-on: 20190201192935.18394-1-mreitz@redhat.com
> 
> I have verified that this doesn't appear to break the existing driver:
> ssh connections to block devices still work as well as they did before
> (which is to say, not very well, I wish we would replace this driver
> with Pino Toscano's reimplementation that uses libssh1).
> 
> However I wasn't sure how I could trigger the bdrv_refresh_filename
> code path, so I don't think I tested that.

One test case goes like this:

Before this series:

$ ./qemu-img create -f qcow2 /tmp/base.qcow2 64M
$ ./qemu-img create -f qcow2 -b base.qcow2 /tmp/top.qcow2
$ ./qemu-img info ssh://localhost/tmp/top.qcow2
image: json:{"driver": "qcow2", "file": {"server.host": "localhost",
"server.port": "22", "driver": "ssh", "path": "/tmp/top.qcow2"}}
[...]
backing file: base.qcow2 (cannot determine actual path)
[...]
$ ./qemu-io ssh://localhost/tmp/top.qcow2
can't open device ssh://localhost/tmp/top.qcow2: Cannot generate a base
directory for ssh nodes


So the filename is weird and you cannot open overlays with relative
backing files.

After this series:

$ ./qemu-img info ssh://localhost/tmp/top.qcow2
image: ssh://maxx@localhost:22/tmp/top.qcow2
[...]
backing file: base.qcow2 (actual path:
ssh://maxx@localhost:22/tmp/base.qcow2)
$ ./qemu-io ssh://localhost/tmp/top.qcow2
qemu-io> quit

The filename looks better and the image is usable.

Max


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